package test;


import java.util.Scanner;

public class ok1 {

    public static long main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int i = scanner.nextInt();
       long[] arr = new long[i+1];
       arr[0] =1;
       arr[1] =1;
        for (int i1 = 2; i1 < arr.length; i1++) {
            arr[i1] = arr[i1-1]+ arr[i1-2];
        }
        return arr[i];


    }


}
